The present invention relates to a product packaging device which has a product supply line and a supply line for packaging materials for a tube-like packaging material and which in order to seal off the packaging material after a filling, is equipped with at least two sealing elements movable relative to one another, of which at least one of them has a thermal sealing element for carrying out the sealing process.
Such devices are used, for example, to fill fruits or vegetables in reticulated or tube-like packaging materials. After a set quantity of the product is fed in, the tube-like packaging material in each instance through the effect of heat is provided with sealing points at right angles to the longitudinal direction of the packaging material, at which points the individual packaging bags can subsequently be separated.
The impact of the thermal sealing element as a rule occurs in such a manner that first the sealing elements with clamping jaws are moved toward one another and then clamp the packaging material in the region for the intended sealing. Following this, the thermal sealing element is activated and the fusing process is carried out. After the thermal sealing element has been deactivated, it is necessary, in order to achieve a satisfactory stabilization of the material, to apply pressure for a given length of time.
Because of the need for a stabilization period following the active thermal sealing, the speed of the packaging process suffers. For this reason it is also known in the art for several pairs of sealing elements to be employed, so that the packaging process can continue during this rest phase. Typically, during the rest phase the sealing elements are moved with the clamped material to be packaged out of the sealing position and an additional pair of sealing elements is simultaneously moved in the direction of and into the sealing positioning. These types of packaging devices with two pairs of sealing elements are summarized, for example, in the journal Neue Verpackung 10/91 pp. 24-41 in the article "Innovationstrends bei Verpackungsmaschinen dargestellt am Beispiel der Schlauchbeutelmaschinen" (Innovative Trends in Packaging Machines as Illustrated by the Example of Tube Bag Machines).
The relevant packaging devices cannot meet all demands, however, such as a high packaging speed and reliability and stability against disruptions that are placed on these machines.
The object of the present invention, accordingly, is to construct a device of the type mentioned above in such a manner that it will carry out the packaging process at a high speed and also will offer good reliability and adaptability when put to various applications.
This object is solved in the present invention by locating two pairs of sealing elements facing each other on separate carriers, by providing for two separate controls each for the opening and closing movements of respective pairs of sealing elements and adjustment movements of the carriers and by having one of the sealing pairs opened and the other one closed when the carriers are moving in counter directions to one another at least during positioning on the same carrier level, with the result that the sealing elements of the opened sealing pair are guided lateral to the sealing elements of the closed sealing pair.
By the use of separate controls for the opening and closing movements of the sealing elements on the one hand and the adjustment movements on the other it is possible, for example, to execute the prescribed opening and closing movements of the sealing elements with a horizontal movements of the sealing elements and a vertical positioning of the carriers to any positions desired along the vertical movement of the carriers. Through this means the batch to be fashioned from the tube-like packaging material can be adapted to various sizes of batches.
In that the closed sealing pair and the opened sealing pair are guided by one another a simple kinematic operation is realized, which guarantees a high degree of reliability even under adverse conditions of use. This simple kinematic operation also supports the processes of movement to ensue a high speed. In addition, closed rotation routes can be set for the sealing pairs, so that the forward and backward movements delaying the courses of movement can be avoided.
A forced synchronization for purposes of mechanical simplicity can be achieved by letting the sealing elements of each sealing pair be moved in contra-rotation relative to one another.
One robust embodiment is provided by having guide rods situated parallel to one another for performing an opening and closing movement of the sealing elements.
In addition, a high degree of security in operation can be afforded by locating vertical rods for executing a vertical adjustment of the mounting plates supporting the sealing pairs.
The manner in which the mounting plates are guided rotating in opposite directions in equilibrium makes low wear and tear operation possible as well as minimizes energy consumption.
In one simple embodiment the product supply line is formed in the shape of the inside of a tube.
The number of structural elements used can also be reduced by letting the supply line of packaging material be formed in the shape of the outer surface of a tube.
A forced synchronization in carrying out the opening and closing movements can be achieved by coupling the carrier arms for holding the sealing elements together with one another by means of pivoting levers.
It is suggested for purposes of guaranteeing a short cycle period that the thermal sealing element is guided to seal a batch already filled in an upper region simultaneously with a batch not yet filled in a lower region.
A further simplification in function can be achieved by coordinating the operating sequence in such a manner that the sealing pairs are equipped with a control for coordinating a simultaneous hold on one sealing area of the packaging material and a withdrawal of a batch to be refilled from the packaging materials supply line.
High flexibility in adapting to various batch sizes is also achieved by having the sealing pairs connected to a control for signaling an opening movement when a set section of a vertical movement has been reached.